Washington — The success of the surge of American troops in Iraq is putting pressure anew on the Pentagon to build a surge plan to counter a resurgent Taliban in Afghanistan. But experts warn that it will take more than just additional troops to turn things around there.

US military officials are scrambling to devise a plan to send as many as three brigades to Afghanistan by next year, with Defense Secretary Robert Gates saying last week that he would send more forces "sooner rather than later." Presidential hopefuls Barack Obama and John McCain have in the past week voiced support for an Afghanistan surge, with Senator Obama, who just visited the country, calling the requirements there "precarious and urgent."

But a surge for Afghanistan, analysts say, must also recognize that the insurgency there – as well as the NATO command structure – is not like that in Iraq. And without a new strategy, the deployment of more forces won't mean much, they say.

"Afghanistan is not Iraq, and you cannot just template Iraq's solutions onto Afghanistan's problems," says Fred Kagan, a senior fellow at the American Enterprise Institute in Washington, who played a direct role in shaping President Bush's surge strategy for Iraq in late 2006. The surge for Afghanistan, like the one implemented for Iraq last year, must not only mean more forces but also a proper counterinsurgency strategy that defeats the insurgency by isolating insurgents from the population, Mr. Kagan says.

The NATO-led mission in Afghanistan had in many ways failed to recognize that the violence amounted to an insurgency, and it has struggled to get its arms around the fight. Now, recognition is increasing that the violence must be countered with a proper counterinsurgency strategy, but there are no simple solutions. Mounting such a strategy will be challenging in Afghanistan, where the NATO-led mission has a labyrinthine command structure made up of 40 countries with divergent political and military views. In Iraq, one top American commander essentially calls the shots.

Pentagon officials are considering significant changes to the command structure in the NATO-led mission. In the coming weeks, the US four-star general who leads the NATO command, Gen. David McKiernan, will probably be given a new command relationship with US Central Command in Florida. The aim is to give a more cohesive, if not American, influence on the mission.

"With everything that we face, I think that has to happen. It's going to streamline," says one senior military officer who didn't want his name used because he was commenting on an active proposal.

And in a sign that the United States is still pushing for more control of the troubled southern sector of the country, where the fight against the Taliban and other "anticoalition militias" is the most violent, the US is considering installing a new deputy commander to work under the NATO commanders there to help focus efforts. These and other proposed changes to the command structure would help "clean up the spaghetti sandwich," as one retired officer put it.

As part of mounting a proper counterinsurgency strategy, analysts and military commanders are also calling for a more coordinated approach – one in which combat action complements reconstruction and aid.

Still, in the end, more troops will be necessary in Afghanistan, military experts and analysts say. The first of those three brigades, possibly amounting to more than 10,000 troops, could be deployed by the end of this year, defense officials say.

But the senior military officer says no decision on troops will probably be made until October, when Gen. David Petraeus, now the top commander in Iraq, will make a final assessment, before leaving that post, about the number of troops necessary for Iraq. That assessment will largely determine what size force can be deployed to Afghanistan, where there are now about 63,000 troops – about half American.

When General Petraeus becomes head of US Central Command this fall, he will add Afghanistan to his portfolio of responsibilities. Many had feared that the Afghanistan mission could suffer under Petraeus in his new role since he might favor the Iraq mission, for which he was chief architect. But he has already begun to ponder what can be done in Afghanistan, sources say.

"Petraeus is absolutely thinking hard about Afghanistan," says an officer who is knowledgeable about Petraeus's thinking but didn't want to be named due to the sensitive nature of the issue. "It would be criminal if he wasn't. They're both his baby now."